This invention relates generally to an air filtering device, and in particular to a device for cleaning an air filter in the dirty-air chamber of an industrial dust collector.
Dust collectors are used to filter particulate out of air that is drawn from various sources including fume and ventilation hoods used in industrial applications such as welding and chemical and pharmaceutical processing.
Currently, air filters located within a dirty-air chamber of a dust collector are cleaned by injecting the filters with a blast of air. This air blast dislodges dust and particulate matter that has accumulated on the filter by impacting the sides of the filter or by creating a pressure differential within the filter such that the air pressure inside the filter is greater than the pressure outside. This pressure differential causes the air within the filter to expand outward thereby blowing the dust off of the outside of the filter.
While the injection of air is a useful way to clean the filter, such a cleaning is more effective when the air filters are oriented in a vertical direction as opposed to a horizontal or non-vertical direction. This is because filters oriented horizontally tend to accumulate the majority of the particulate matter on the surface nearest the top of the filter. As such, when these filters are changedxe2x80x94due to the concentration of dust and particulate on the top third of the filterxe2x80x94the bottom two-thirds of the filter are relatively clean.
In addition to air cleaning, filters are cleaned by shaking mechanisms such as those disclosed in U.S. Pat. No. 4,579,570 (Klaas), U.S. Pat. No. 4,340,401 (van Weelden et al.) and U.S. Pat. No. 4,199,334 (Berkhoel). These shaking mechanisms employ mechanical devices such as rods or plates to shake the filters in order to loosen dust accumulated thereon.
Other means of cleaning filters involve rotating the filter through the use of an electric motor. Such a method is disclosed in U.S. Pat. No. 4,222,755 (Grotto) and U.S. Pat. No. 4,661,129 (Nederman). Because of the motor output required to rotate a filter, such devices are useful only for small filters such as those found in internal combustion engines.
The rotation of a filter through the use of a turbine is disclosed in U.S. Pat. No. 3,898,066 (Miskiewicz). In Miskiewicz, turbine blades which are attached to a cover plate extend beyond the filter which is located in a housing. Such turbine blades are coupled via the cover plate to the filter thereby allowing the blades to rotate the filter. Although Miskiewicz employs a turbine, such turbine is located outside of the filter. Thus, any air used to turn the turbine cannot be used to clean the filter by way of injection into the filter. This results in an inefficient use of the air.
Devices that allow for the filter to be rotated at some regular interval allow for a more even distribution of the dust and particulate over the filter thereby increasing the operational life of such filter. This helps to reduce operating costs associated with the operation of the dust collector as the filters have to be replaced less frequently. A device that rotates cleaning filters used in a dust collector so as to allow for a more even distribution of dust and particulate on the filter would be an important improvement in the art.
An object of the invention is to provide an improved dust collector that overcomes some of the problems and shortcomings of the prior art.
Another object of the invention is to provide an improved dust collector that extends the useful life of an air filter.
How these and other objects are accomplished will become apparent from the following descriptions and from the drawings.
This invention involves an improvement to a dust collector for removing particulate from air. The dust collector includes a housing that encloses clean-air and dirty-air chambers. An elongate non-vertical annular hollow filter with an end accommodating the flow of clean air is positioned in the housing. A nozzle connected to an air source is positioned so as to inject a blast of air into the filter in order to dislodge particulate accumulated on the outside of the filter.
The improvement comprises a turbine positioned within the filter and linkage joining the turbine with respect to the filter such that a blast of air from the nozzle turns the turbine which thereby turns the filter so that the filter is reoriented to facilitate removal of particulate collected thereon.
In one embodiment of the invention, the linkage is comprised of a turbine shaft positioned within the filter and connected to the turbine. A drive cover is attached to an end of the filter opposite the flow end and a drive plate connects the shaft to the drive cover. In a specific version of such embodiment, a coupling extends from a turbine and a gear train is connected intermediate the coupling and the turbine shaft. In a more specific version of the embodiment, reduction gearing is used to facilitate rotation of the shaft. Such reduction gearing can include a first spur gear attached to the coupling, a second spur gear interacting with the first spur gear, a jack shaft connecting the second spur gear to a third spur gear and a fourth spur gear connected to the turbine shaft and interacting with the third spur gear.
In another embodiment of the invention, a plurality of air bearings connect the end of the filter accommodating flow to a wall. Each of the air bearings is comprised of an air-bearing port on the side of the wall outside of the dirty-air chamber, a slotted ring between the wall and the filter and a sealing element attached to the first end of the filter. In a specific version of this embodiment, a plurality of auxiliary air lines are attached to the air source in such a manner that they surround the nozzle, at least one of the auxiliary air lines is routed to a manifold which then directs the air to the air-bearing ports. In another version of such embodiment, the remaining auxiliary air lines are oriented so as to direct air flow toward the outer edge of the turbine.
In still another embodiment of the invention, the filter is positioned on a support frame located within the housing.
In a preferred embodiment of the invention, the housing of the dust collector includes a door wall defining a passageway, an outer door engaged with the door wall to substantially seal the passageway and a spring assembly connecting the door to the drive cover. In such an embodiment, the spring assembly includes a first set of guide pins having proximal and distal ends. The proximal ends of the pins are attached to a stop plate while the distal ends are connected to the door. A compression spring is positioned between the door and a spring backing plate within the first set of guide pins. A second set of guide pins are attached to the drive cover and extend through the stop plate and the spring backing plate into the dirty-air chamber. Such guide pins have proximal and distal ends with a retainer at the distal end and at least one of the pins extending through the drive cover and being affixed at its proximal end to the drive plate, whereby torque is transferred from the turbine shaft and the drive plate to the drive cover.
In still another embodiment of the invention, at least two filters are positioned in the housing. These filters are oriented end-to-end and a sealing element seals the two filters together.
The invention also involves a method for cleaning a filter located in a dust collector. Such method is comprised of the steps of: (a) positioning a turbine within the filter; (b) linking the turbine to the filter; (c) impacting the turbine with a blast of air thereby causing the turbine to rotate; and (d) imparting the rotation of the turbine to the filter by means of the linkage, whereby the rotation causes the particulate accumulated on the filter to fall into the collector.
In one preferred embodiment of the method, the blast of air is generated through a nozzle. In a more specific version of such embodiment, the air blast is generated through a nozzle in combination with a plurality of air lines.